Yes, you should amend your tax return to indicate that you can be claimed as a dependent (see attached screenshot).
Your mother should file her tax return by mail as she cannot e-file as long as your amended return is not processed by the IRS.
Please see the
following TurboTax FAQ for
instructions on how to amend your tax return in TurboTax.
https://ttlc.intuit.com/replies/3288565